Mitt Romney:The GOP's Pro-Science Candidate

As many news outlets are reporting (see, e.g., here), GOP presidential candidate Mitt Romney has publicly broken from Republican Party orthodoxy by proclaiming that climate science demonstrates the need to reduce anthropogenic greenhouse gas emissions. His willingness to follow the scientific data, as opposed to political expediency, is both refreshing and laudable. I cannot help wondering, however, why he would buck his party on climate change, while kowtowing to it on health care, disavowing policies that are embodied in a law he championed and signed as Governor of Massachusetts. As a matter of political strategy, I find his comparative positions on climate policy and health care reform puzzling. What's his calculus?